Artifacts are the main objective from a (non-Grand) Heist. The Artifact you’re seeking will be shown on the contract before the Heist commences. If you complete the Heist successfully with Artifact in hand, you can turn it into Faustus, the Fence at the Rogue Harbour in exchange for a sum of markers greater than you paid to run the Heist. Artifacts do not have any other gameplay function.
The main thing you need to do is complete regular Heists by reaching the Artifact and turning it in for profit.
When you trigger the alarm, you’ll have a short window to continue stealing things before the facility goes into lockdown. If you’re close enough to the Artifact, this means that you can still grab it before lockdown goes into full effect. There are also mechanisms in play that can extend or modify the amount of alert required to reach the maximum alert level.
If you successfully complete a Heist and turn in the Artifact, you’ll also receive a sum of Markers greater than you paid to run the Heist.
Yes, you can but you won’t be considered to have completed the Heist unless you escape legitimately with the Artifact. Your contraband (and Artifact) will be dropped on the ground as you log out.
This happens when you smash the case that contains the Artifact so it’ll apply equally for all party members even though multiple Artifacts are dropped if you have multiple party members. Your alert level is also shared between all party members.